Honeycomb Filter Catalyst Thickness Distribution
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Solution Overview
Problem
Existing exhaust gas treatment devices face challenges in enhancing purification performance while minimizing the reduction in engine scavenging performance, as increased catalyst support on downstream sides of honeycomb structures leads to ventilation resistance and engine efficiency issues.
Innovation Solution
A device with a catalytic converter and filter system where the catalyst is thickly supported on the filter surfaces and thinly on the inner surfaces of pores, using Pd-supported La2O3-containing alumina and Pt-supported La2O3-containing alumina catalysts, allowing for efficient oxidation reactions and reduced ventilation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the catalyst is thickly supported on the cell walls on the downstream side of the honeycomb structure, then the purification performance of exhaust gas is improved, but the pores of the cell walls are blocked, increasing the ventilation resistance of the exhaust gas
Solution Approach 1:
The patent applies local quality by differentiating the catalyst support thickness in different regions of the honeycomb structure. Specifically, the catalyst is supported more thickly on the downstream side cell walls where purification is needed, while maintaining thinner support on the upstream side to preserve ventilation resistance. This spatial differentiation of catalyst density resolves the contradiction between purification performance and exhaust flow efficiency.
2Reliability
If the amount of catalyst supported on the downstream side is increased to enhance purification performance, then exhaust gas purification is improved, but the scavenging performance of the engine is reduced due to increased exhaust pressure loss
Solution Approach 1:
The patent implements local quality by optimizing catalyst distribution across different zones of the exhaust treatment device. The catalyst is concentrated on the downstream side where it can effectively purify exhaust gases without excessively increasing overall pressure loss, thereby maintaining engine scavenging performance while achieving desired purification levels.
Solution Approach 2:
The patent addresses the contradiction by transitioning from a uniform catalyst distribution approach to a spatially differentiated distribution across multiple dimensions of the honeycomb structure. By varying catalyst thickness in the axial direction (upstream vs. downstream) and radial direction (cell wall vs. pore), the system achieves both high purification performance and acceptable pressure characteristics.
3Reliability
If the catalyst is supported on the inner surfaces of the pores of the filter, then the purification of exhaust gas is enhanced, but the pores become clogged, increasing the ventilation resistance
Solution Approach 1:
The patent applies local quality by selectively supporting catalyst on different surfaces of the filter structure. The catalyst is supported on the outer surfaces of cell walls and selectively on pore surfaces, creating localized catalytic zones that provide purification functionality while preserving sufficient pore openness for exhaust gas flow, thus balancing purification performance with ventilation resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration ensures effective purification of exhaust gases with minimal increase in exhaust pressure loss, maintaining engine scavenging efficiency and reducing the need for device upsizing, while efficiently oxidizing unsaturated and saturated hydrocarbons at varying temperatures.
Implementation Method 1
a first catalyst which exhibits activity in oxidation reaction of unsaturated hydrocarbons whose number of carbon atoms is 6 to 9
Implementation Method 2
a second catalyst which exhibits activity in oxidation reaction of saturated hydrocarbons whose number of carbon atoms is 5 or smaller
Implementation Method 3
a filter porous and collecting particulate matter in exhaust gas and a filter container housing the porous filter, the exhaust gas passing through pores of the filter from surfaces of the filter and being discharged
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A honeycomb-like porous filter for collecting PM in exhaust gas is provided in an exhaust gas passage of an engine. The exhaust gas flows from inflow side cells 12 of the filter through pores 16 of partition walls 15 of the filter to outflow side cells 13. A catalyst 17 is supported on surfaces of the partition walls 15 constituting the inflow side cells 12 and on inner surfaces of the pores 16 of the filter. The catalyst 17 is supported on the surfaces of the partition walls 15 more thickly than on the inner surfaces of the pores 16.